What were the causes of US intervention in World War 1?

The U.S. was a neutral country in the begining of the war. They got involved because they felt that their status as a neutral contry had been violated because the British passenger ship called the Lusitania was sunk by a German U-boat. U.S. citizens were aboard and died. In turn, this is what caused Americans to waiver in their stance on neutrality. This is just a summary of it. A Problem The Lusitania was sunk in May 1915, and the U.S. declared war on Germany in March 1917. It's perfectly possible that the sinking of the Lusitania marked the start of a decisive shift in opinion in America, but it can't possibly have been the reason for the America declaring war on Germany. Try 'unrestricted submarine' warfare instead. THE REAL REASON WHY AMERICA ENTERED THE WAR America did not enter the war after the sinking of the Lusitania. In fact, President Wilson still remained neutral after the sinking but warned Germany to stop using submarines or in fact they would enter the war. It was two years later, in 1917, that a telegram was intercepted by the British. The telegram was called the Zimmerman telegram and was from Germany on its way to Mexico. The telegram was asking Mexico to join the war and be on Germany's side and in return they would give them Arizona, New Mexico, and Texas. But since the British were our Allies, President Wilson immediately got Word. Another reason for entering the war, is that Germany also started using submarines again in 1917. As well as Tsar Nicholas II abdicated. Leaving Wilson to join a mostly democratic alliance.